The office of San Francisco Mayor London Breed said Wednesday it is "unfortunate" that Osaka has decided to terminate their sister-city relationship over a statue symbolizing Asian "comfort women," a euphemism for the girls and women forced to work in Japanese military brothels before and during World War II.

"It is unfortunate that (Osaka) Mayor (Hirofumi) Yoshimura no longer wishes to maintain ties between the governments of San Francisco and Osaka," Jeff Cretan, Breed's communications director, said in a statement.

The San Francisco mayor's office received a 10-page letter Tuesday from Yoshimura giving notification of the termination before what would have been the 61st anniversary of the sister-city relationship.